Tailerons pitching up when flying straight and level

[bkthunder]

Aren't the tailerons pitching a bit too much when flying straight?

The whole point about the F-16s relaxed stability is so that tailerons stay in a mostly neutral position most of the time, thus reducing drag. Doesn't seem the case here?

 

Some pictures for reference, look for the painted mark on the fuselage, just fwd of the taileron's leading edge:

 

Edited November 10, 2019 by bkthunder

[razo+r]

What was your speed?

 

Cause if you don't have much of that, I assume that the pitch could be that high up at 40K feet.

 

Or maybe try at lower altitude, how does it look there?

[Stubbies2003]

Aren't the tailerons pitching a bit too much when flying straight?

 

The F-16 FLCS will adjust surfaces to maintain control of the aircraft many times per second.

 

 

The whole point about the F-16s relaxed stability is so that tailerons stay in a mostly neutral position most of the time, thus reducing drag. Doesn't seem the case here?

 

 

Uh NO. The whole point of RSS is to enhance the maneuverability of the aircraft. In doing so this also makes the aircraft inherently unstable thus the requirement for the FLCS to adjust the surfaces to maintain control.

 

An example of the F-16 doing this:

 

An example of the F-35 doing this starting at 1:21:

Edited November 10, 2019 by Stubbies2003

[Frederf]

If the AOA is 3 degrees then tail at -3 degrees is the least drag. The tail being neutral relative to the airframe longitudinal datum causes the AOA of the tail surface to be equal to the airframe. The tail being equal and opposite the airframe AOA causes the tail surface to be inline with the air flow.

 

But at the end of the day the tails are providing the positive or negative lift required for pitch torque to maintain whatever result FLCS commands. Because COM and COL are so close together in the F-16 the pitch input for zero pitch rate in this static situation like level flight the tail trim is probably going to be nigh imperceptible. Presumably as CG shifts the amount of tail moment will change but again probably almost impossible to see by eye. One can also assume that because COL and COM are so close that the angle of the tail surfaces relative to air flow should be near minimum (because little if any torque and thus tail lift is needed) as we see.

 

Now there is some theory that the tails could provide some lift relieving the wings from that but any lift the tails provide has a pitching moment so the system is constrained. They have to provide whatever lift is needed for pitch balance. That is unless there is some other pitch moment surface (LEF, TEF, etc.) that can cooperate with the tailerons to share the pitch moment duty and be in a combined minimum drag config. And as far as I know, that isn't the case.

[Eldur]

What the mark represents?

 

Most probably the 0° position.

 

What was your speed?

 

Cause if you don't have much of that, I assume that the pitch could be that high up at 40K feet.

 

Your assumption was dead on. But 493KIAS is quite some up there. Check the screenshot, it has the info bar on at the bottom, showing just what you asked for

 

Would still be interesting to compare this to some other alts and speeds. At least in the transsonic region I'd not wonder about more pitch up on the tailerons. But this definately is past transsonic. A lot.

[razo+r]

Well, how do you know it's IAS, and not something else?

[bbrz]

Well, how do you know it's IAS, and not something else?

Because the screenshot says IAS?

Edited November 11, 2019 by bbrz

[macedk]

F-16 try to maintain 1.0g at all time .